High temperature fan



Oct. 2, 1945-. c. NYGREN HIGH TEMPERATURE FAN Filed April 21 1945 v -8 sheetssheet 1 l 1 11 r/ ,1 1/ 1 1 11, 1 1 ,1 .1 1 ,1 11 .1 1,1 ,1 f 1 1 1/ 11 1 1 l l l l/ 1 1 1/ r 1 1 IVENTOR. 'l fig/Z C. NYGREN HIGH TEMPERATURE FAN Oct. 2, 1945.

Filed April 21, .1945\ j Vssheets-sheet .3

Oct. 2,1945'. c; NYGREN 2,385,838)

HIGH TEMPERATURE FAN Filed April'zl, 1945A 9 sheets-sheet 5v 70 5)'0 5f)- 70 l,... i I,

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Oct.` 2, 1945. (c. NYGREN 2385338 j.

y HIGH' TEMPERATURE FAN` Filed April 21,.w 1945 9 snefsfshet I Y 'I 1945. y f C..NY GREN l 2,385,838

HIGH TEMPERATURE FAN Filed Apri1 21, 1945 v s sheets-sheet s WW i www 1 [55 11M 'WW t NNW y Oct. 2, 1945". c.' NYGREN 2,385,833

HIGH TEMPERATURE FAN l Filed April-21,v 1945 9 sheets-sheet 9 figo/'gaga Patented Oer. 2, 1945 i man TmnaaTUns FAN om Namen,v wenn om, ma., muur te Michiana Products Corporation, Michigan City,

Ind.; a corporation of Indiana Appueeuen apen :1, im, sensi Ne. seams cnam icl. 23o-184i e This invention relates to centrifugal fans or blowers for heat treating furnaces, and has for yits prlncipaiobject to provide an improved arrangement of hub members and blades whereby the latter are securely made fast against outward movement under centrifugal force and against turning movements withrespect to the hub that will safely` endure the rigorous conditions inservice at high speed and high tem-` perlttlires.v Generally speaking, this is accomplished (by giving the hub members a wide grasp on enlarged, somewhat delta shaped inner por# tions of the blades and providing positive fastening means between the hub members and the blades at points equidistnt from the axis to preservedynamicbalance.\ l

'l'his applicationis a continuation in part oi Ser. No. 536.801, illed May 22. 1944.

In the accompanying drawingsl Fiss. 1 and 2l are diagrammatic views of a double inlet fan and its associated parts in one form of installation; s y y Fig. 3 is a longitudinal sectional viewthrough a fan and hollow shaft of the preferred construction;

Fig. 4 is a perspective view of one' of the hub Fig. 16 is a front elevation of one ofthe blades used in Fig. 15; Y i

Fig. 17 is an end view of that blade .looking from the top in Fig. 16;

Fis. 18 is an edge view of that blade from the right in Fig. 18;

Fig. 19 is a longitudinal section through aliother double entry fan corresponding to Fig. 3,y but showing still a diii'erent means for cross' fas- -tening the blades to the hub members; 8

Fig. 20 is a frontclevation of one of the usedin the 1an inFig. 19;v

Fig-.V21 is an 'edge ,view er the bieder shown in l Fig. 20 `looking from the right in that iigure;

Fig. 22 is a longitudinal section through anv other ian' similar to Fig. 3 but showing a dilerent form and construction ot shroud; l Fig.` 23 is a part section and part elevation of the ian shownin Fig. 22:

Fig. 24 is a front elevation o! one ci the blades usedintneranmnaamportions for securing the blades together and te the shaft, as'shown in 1718.3;

VFig.5isa.part side'elevationandpartsection takenonthecenteriinetransversetotheaxis of rotation; I'

Fig. 6 is a perspective view of one of the blades in the preferred form of construction;AV Y Fig. 7 is a fragment/of-fon/ iorm or shroud;

f a sectional viewvcorresponding to Fig. 3 of a single inlet fan ofthe preferred construction;

Fig.9isaper'spectivevlewofoneoftheblades I inasingleinlet ianshowninl'ig.8;'

Fig. 10 is a fragment of a shroud at 'thel inlet' side of the fan;

Fig. 11 ia a fragment. of the shroud at the opposite side of the fan;

Fig. v12 is a longitudinal section through a fan and hollow shaft corresponding to Pig. 3 except for a diil'erent means to cross fasten the blades l to' the hub members;

bersused in the ian shown inlig. 12;

Fig. i4 is a half longitudinal section through the'hubmember shown in Pig. 13; Fig. 151s a part side elevation and part section taken' on thel center linetransverse to the axis'in Fig. 12;

pag.13 is a race view er eneef the nubmemne. z5 is en edge view er the meses :hewn in Fig, 24 looking from the right in that figure:

Fig.v26 is an end view of the binds shown in Fig. 24 looking downwardly on that ligure.

These particular forms and the corresponding description are chosen for the m of disciosure only and are not intended to impose unlimitations on the' claims, for it is fully appreciated that the substanceofthe-lxvention can be embodied in many other forma.

In Figs. 1 and 2. Il indicates a conventional `form of masonry installation for a fan or blower within which is a metal-casingl il fora double inlet'i'an I2 mounted on a hollow water cooled .shaft n, icumaled in bearings u and driven by a meter is through a .v-belt driven. inlet side of a lwater cooling unit is shown ygenerally at l1, and the return sidefis shown-generally at Water cooling'is ordinarily usedin fan 'com struetions for propelling high temperature iluilk such asthe gases circulated inheat'treating iurnaoes d' The detailA er the preferred :om or double fan is shown in Figs. 3-7 (Sheets 2 and l). 'lhe fan is composed of twelve blades, generally-indi# cated by ,twe ciremarshrouds lhsndtwen'ub portions l2, assembled on a hollow shaft Il.

rnngsasnaaitwmbeseentmteeenbnoef is composed or. a generally iiat plate having an inner portion or foot I4 provided with outwardly converging [eide edges Il by virtue of which it be comes somewhat wedge-shaped or delta-shaped isis Each'edge llisprovided withiiangesormachim' i ten they v@stamina and maintain dynamic bait ance.

' l another, the thinner portion ofv inner portions 66. The extreme inner edges l1 of the blades 85' betwenthe ribs copending application and these aligned openings' receive fastening i dowel pins 6l. twenty-four of which positively l l fasten and hold the blades against outward under centrifugal force. Those "pins, l0

are in circular arrangement about the axis of rotation, and thus in th'emselves and in the like, i-

or practically identical, blades which they fas- "rne 'main body of theinner portion orr foot 54 of each 'blade is thickened relative to the outer l l portion B2, the 'inner portion being on the order of .thick and the louter portion on the order 1 i of M4" thick. The change in thickness is made go very gradual to avoid any abruptness. and avoids t l 3 ing abruptness is the rule throughout this `fan r construction. And, while no distinct line can be indicated forthe change from one thickness to roughly bounded by the line I in' Figs. 3 and 6.

The machining pads Il and the-sector-shaped flanges 51 are Joined' to the inner portions M by ,t gently curving fillets` Il, generally indicated by l`shading. t-In orderto providemetal andstrength 30" about the inner ends of the openings Il, bosses l 65 are provided adjacent to th'e'sector-shaped anges 61, and they are Joinedtothe thinner l byother gently curving illlets are comparatively straight, and together' thel twelve of them form a sort of polygon around the shaft lS-but spaced from it, as appears iii- Iilgs.`

3 and 5. The flanges I1 are slightly longer than the intervening portions Il.

A `iiit or adjacent 'to each side e'dge, each bladeis thickened and providedwith grooves Il. wherev by at eachk side of each ,groove there appear ribs 68 and v1li. thfe ribs 10 being relativelyshort andl shrouds are wide atv proximately as long as the are about the depth.

their edges,. and the former of theslotsingthe shrouds. r Each shroud ill 4is a ringl provided with olit-y escasas change of surface that vrmight foster cracks. The tit between th'e sides of the slots and 4the machined faces B8 is close and, together with the dowel pins Bi; provides a strong driving and holding joint between the hubs and the blades. 'Ihe chined faces I6 being remotefrom the axis of rotation, minor accumulations of tolerances have less effect than they would if 4those surfaces were close to the axis. Thus. the construction insures accurate and positive placing and holding ladiacent surfaces of the slots 15 and the maof the blades in their relative diverging positions with respect to the hubs in accelerating. driving, f

and decelerating. This accuracy also contributes to the smooth support of the shrouds 5l on -y the twelve blades, ,both in operation and in expanding and contracting.

Each hub portion 52 has a bore .11 to receive a v shaft I3 to which it is keyed. The left hub portion `l2 inFig. 3 rests against the shoulder 18 i on the shaft. and the right hub portion in Fig. 3

is held against the blades by a large locking collar 10, made fast by a lock nut 80 vand a lock washer.

` Il having one'tab I2 fitting in one of the key slots the blade lis jgs ktions and corrected by empirical data.

inthe shaft Il and other tabs 83 and 84 bent into therespective Vnotches 85 and 85' in the lock nut tand the locking collar 19. l Ininitial asthen backed oilenough to provide for expansion. which can be initially determined by calcula- 'rh :an shaft is water encies ,and is man@ of carbon steel. The hub portions |52 are of suitable alloy.' The -sliaft and the hubs. therefore,

have different coemcients of expansion. The

tendency thus createdto increase the clearance 'sembly. the collar 1g, is setup wrench tight and i between the hub-portions and theshait as the.

fan is heated u'p is greatly augmented by the fact that the shaft iswater cooled and the hubs are not. Bearing in mind that allof theian is carried by the hubron the .shaft andthat-a 30-lnchffan. substantlallyas shown-in Figs. will weigh on vthe order of 650pounds, it is apparent that a slight ecoentricity between the hub Portions and the ribs se relatively ions. 'maintenu-e ap- 45 the shaft results in enormous forces due to lack of dynamic balance. i

To prevent this conditionr and to obtain and l maintain dynamic balance. three or more keys or 7 vsplines are used to eilect a driving connection bewardly opening slotsf1i, twelve in number, vtore-elo ceivey the side edges of the several bladesas the adjacent portions of the shrouds are received v and 10. The. shrouds are of uniform thickness to about the depth of the slots.

1I, and from'there inwardly they are graduali! 56 wthickened, as indicated at 12, to provide addi.-

tional s ngth for resisting the bursting tend-` encies 'of centrifugal forceon tlie shroud as aQ whole. 'f i An alternative to this construction is shown oo 19, 1945, land in Figs. -22-36 (Sheets` 8 andi). Others will-be readily designed to suit particular conditions and to lmeet individual'preferences.

' The flange 0I of each hub portion inner'at face 13 for contacting with and bearing against the" grouped faces I1 fof the blades. 4 outwardly of this face 13, which is at right to th'e`axis, each flange has an inclined face 14 provided with twelve hold the machined 'faces Il of the converging edges il of the-inner portions of the blades.

Whilev the slots are backed by a considerable ckness of flange metal; the inner portionsk are v ounded at the corners 1I to avoid any abrupt Ser. No.' 594,750, med

hssano slots 1l to receive and l0 keys will'be machined to tween the shaft and the hub portions. In Figs. 3 and 5, keys are shown.- and they willr probably be most used, and preferably the keyways yand give contact 4at the side faces only. the outer faces-being free radially. lIn'thisinstancia*` the three keys are arranged at degrees on cetera--andareshown as they simplest form. keys arranged 't"90degrees,

oncenters. etc., are-contemplated. Three keys is the smallest number that will fairly insure and maintain dynamic balance.

As heretofore made in a 30-inch fan, the outer 1 Portions oftheshrouds were .24.5 inch thick with Y an allowance of plus for minusjnoos', and

grooves 08 were the .250 inch with an allowance of plus.003 minus .000. The inneriedges of the shrouds were V2 inch thick, and the corners were ,rounded on a V4 inch'radius. q

B0 ofthe hub por-.f

The slots 1l in the flanges tions were V2 inch wideplus .005' minus .000, -and' the inclined edges Il at thefmachined faces 56 were .498 inchl thick plus .002 minus .000. The

' `sector-shaped flanges were 23126'. The openings 'Irl were 1 inch in diameter reained plus .000 `minus 1.002. The openings were the same. and all the openings were ar- I9' 'in the flange 60 ranged. on'clrcles of an 8 inch diameter. The

Vmachined facesA l! extended to approximately 8 1/2 inches from the axis of rotation and ywere about 1/2 inch wide. y The side faces of the sectorshaped ilanges I1- werevabout a/4 of an'inch wide.

The outer surface of the ilange it on the hub portion was about 70 28 inclined to the vertical. and the inner face of the same ilange was about 60 to the vertical. The inside diameter of the shrouds was 20 inches. There were thus provided ample inlet openings 'at each side somewhat in excess of the discharge opening at the perimeter of the fan. y

The slots 1I in the shrouds were .1% inches deep, or, about 1/3 of the' 5-inch radial width of the shrouds.

Adjacent sector-shaped ilanges l1 are spacedf by an angle 6 34'. i

These and otherclearances and dimensions are given to insure complete disclosure ior one size of fan that has been satisfactory in actual service, butthey are not intended to impose any limitations on the claims.

According to one mode of assembly, the inner hub portion is in place on the shaft against the shoulder 1l. The blades are assembled with the two shrouds and brought'into position with the pins projecting from the' hub flange ll into the openings vin the blades. The other hub ilange is then brought into place: the collar 1l is threaded on; the lock washer slipped into. place; the lock -nut screwed up; and the tabs 33 and 34 bent over. A

A single inlet fan embodying the characteristics of the double inlet fan shown in Figs. 3-'1 is shown in Figs. 8-11 (sheet 4). It corresponds to the double inlet i'an in every particular except that the blades are cut away. atA the right. as shown best by comparing Figs. 3 and 8, and the shroud ISI at the right is wide enough to close the right side of the fan, leaving the entire inlet at the left. Hence, in view of the detailed de-f scription that has been given with respect to the double inlet fan, it will be'suillcient to add the corresponding numerals to Figs. 81l.` Instead of using dowel pins 8l. shown in Figs. 3; 5, and 8, some will prefer to cross-fasten the blades il to vthe hub portions l2 by rings as shown in hub members to eilect the cross fastening..,.A'

reverse 'of this will be preferred by some, as illus trated in Figs. 19 and 20 of application Ber. No

536, 801, filed May 2 2, 1944.

These variations are deemed suiilcient to illustrate how designers and production men will vary the forms while maintaining the fundamental on the inner, delta-shaped portions o! the blades on the faces l5 and Il and supplementing this* by positive cross fastening between the inner -portlons of the blades and the hub members in circular arrangement to determine the exact relation between the several blades and the hub members and maintain that relation in service. According to the preferred construction, the hub portions and bladesr and the shrouds are cast s,sss,ese

from blades and the two shrouds and the two hub portions. respectively, identical. After the machining. the parts should be annealed at a tempera- 5 ture above the highest to be expected in service in. order to remove internal strains that might be released in service and throw the fan out f oi' balance. By weighing the blades and a `slight amount of iitting, the assembly can be readily lo given dynamic balance, and the construction described will insure maintenance of that balance. in service as well as the .necessary strength i'orl a long period of service.

Thepumose oi the pins or rings is to crossfasten the blades in the hubs, making them secure at the same distance from the axis of rotation--in other words, to establish a datum line or datum lines at which each oi the blades is fastened and held against outward individualmovement due to centrifugal force.

Another purpose of making the inner portions l of the blades wedge-shaped and the hubs to cor*-v respond/is to give the hubs a grip on the blades to a great distance .from the axis-of rotation as an element of safety against a blade 4or a portion of a blade getting freeon account of a break across and between the fastening pins or rings.

The inclination of the hub flanges provides the necessary inlet or intake'and gives an intake area in excess of the discharge of the perimeter of the fan in the constructions here illustrated. .Each slot II in the shrouds 1I is of an inch wide. and the bottom is iol-med by s inch drill before the slotting. It is 1% inches deep, and

between the ribs l. and 1l, where it is 1% inches wide. This portion is also 5t of an inch thick,

only unavoidable manufacturing clearance being allowed.

accurately held in place in the slots Ii of the hub flanges Il to a diameter of 15 inches in a Sil-inch fan',.it will be apparent that the shrouds are'borne upon and driven by 12 blades accurately positioned in the open ended slots I I. Being thus borne and driven without any actual attachment.

` formed in sectobshaped pieces individual to the v 56 blades. nach blade lle in this modification has a sector-shaped shroud element Ill provided with `insel-lined faces Il! adapted to make a push Joint .between the iianges lil oi' the fork Ill at the adjacent edge ofthe sector-shaped shroud elel0 variations are more fully disclosed in copending application 8er. No. 594.750,'ii1ed May 19, i945,

where that subject matter is made the basis of claims. I I claim:

l. In a high` temperature centrifugal fan, a plurality of blades in circular arrangement about a common axis of rotation with their outer portions diverging outwardly from said axis and theirv inner portions converging inwardly .toward said axis and terminating in feet which are axially narrower than the blades, said feet lying in the plane of` said axis and having edges diverging inwardly in an axial direction, and hub members 'l5 having peripheral flanges diverting inwardly in suitable alloys and machined to maxe the' receives the corresponding portion oi' the blade Bearing in mind that the machined faces It on, the inner portions of the blades are firmly and ment carried by thenext blade. This and other an axial direction and grasping saidedges ci the 2. In a high temperature centrifugal f an, al plurality of blades incircular arrangement about a common axis of rotation with their outer portions diverging outwardly from said axis and their inner portions converging inwardly toward f said axis and terminating' in feet which are axially\ narrower than the blades, said feet lying in'the plane of .said axis and having edges dlverging inwardlyin an axialdirection, and hub members having peripheral tianges provided with grooves diverging inwardhr inan axial direction vreceiving narrower than the blades, said feet lying in the plane of said axis and having portions provided with thickened edges-diverging inwardly in an axial direction, and-hub members having peripheral iianges provided with grooves diverging'in- A wardly in an axial direction receiving the thickened portions of the edges of the feet.

4. In a high temperature centrifugal fan, a plurality of blades in circular arrangement about a common axis of rotation with their outer porcentrifugal Ian, a.

tions diverging outwardly from said and their inner-,portions converging inwardly toward said sns and emanating in reet.wmch are.

axially narrower than the blades. said feet lying in the plane oi' said axis and having edges diverginginwardly in an axial direction, and a pair of hub members having peripheral ilanges diverging inwardly in an axial dlrectionand ygrasping the adjacent edges of said feet, said flanges termihating peripherallyinwardlyof the blades `and\' 'beingsspaced therefrom to provide an intake for the ian.- l

5.,In a high temperature centrifugal fan, a plurality oi' blades in circular arrangement about a common axis of rotation-with their outer portions converging inwardly toward said axis and terminating in feet which are axially narrowerrr than .the blades, said feet lying in the plane of said axis and having edges diverging inwardly in an axial direction, a pair of hub members having peripheral iianges the outer portionsof which diverge inwardly in an axial direction and grasp the adjacent edges otfsaid'feet, and axially extending cross fastening means interlocklngthe -hub dances andthe feet and establishing a datum line at which each ot the feet is fastened and held against outward ymovement due to centrifugal force.

CARL NYGREN. 

